Video of backfiring after mods and jets

[Appel_1978]

Here is a video of my bike backfiring as i let off throttle. I have ebay exhaust, pod filter, and CSC recommended me going to a 115 from i believe stock was 108 and a 40 and stock is 30 something. Should i go with different jets? I know there is a screw underneath that i needed to cut a slot in should i back it out more or screw it in? any and all ideas welcome

[Appel_1978]

This is what my spark plugs look like after riding a few miles with new jets

[hnu13]

what carb are you using??
what region of the country are you located?
what's the altitude there?

[pete]

it's back fireing on a closed throttle...
most bikes do that these days because of the
exhaust air injection system to burn unused fuel that
enters the exhaust while on a closed throttle to give clean
exhaust emissions..
fuel + air + red hot cat = BANG

You notice it now because the new pipe dose
not baffle the sound of the back fire as much...

just gut the Air injection system off the bike & plug
the air inlet in the head....

You want to hear my XT660R on a closed throttle....


...

[Appel_1978]

Im using stock tt250 carb and and purchased jets from CSC. I am in central Florida about 50 above sea level max. I dont recall hearing it with factory jets though but i have only had the (used 2015) bike for a less than a month and started modding it. (although previous owner did have a random straight pipe off of a smaller 80cc (maybe) but is was loud and barely on the bike just swinging around but i dont think that means anything just giving a back story. Also before, i could start bike just by touching the button now i need to pull on the throttle just ever so slightly. (i have never had to use choke before jet upgrade and after upgrade)

[Appel_1978]

Originally Posted by pete

just gut the Air injection system off the bike & plug
the air inlet in the head....

You want to hear my XT660R on a closed throttle....


...

What does the air injection system look like. are they the hoses going into the side and bottom of the air box. i left them attached even though im not using the airbox any longer

[Sochin]

Just block it off like this on your TT, this is on my Hawk.....but I have a TT250 head on it.

https://photos.app.goo.gl/UJcpNcJEbZKW6gwG7

[bogieboy]

It looks/sounds a bit lean... i would back the air fuel mix screw out a half turn and try it.... looking for a bit more caramel color on the plug... otherwise bump up to the next larger jet size...

[Appel_1978]

Originally Posted by Sochin

Just block it off like this on your TT, this is on my Hawk.....but I have a TT250 head on it.

https://photos.app.goo.gl/UJcpNcJEbZKW6gwG7

so i plug the inlet on the head with a facricated plate do i need to make a gasket for it? and what about the tub going into bottom of air box and into motor? Do i plug that off as well of put a small breather filter on it

[Ariel Red Hunter]

Originally Posted by Appel_1978

so i plug the inlet on the head with a facricated plate do i need to make a gasket for it? and what about the tub going into bottom of air box and into motor? Do i plug that off as well of put a small breather filter on it

I recommend a PCV valve in the line coming from the crank case. Install it so the crank case can breath out but can not inhale...ARH

[Sochin]

Yes, just use high temp copper silicone gasket maker for that blockoff plate, use a small filter on the crancase breather or a PCV valve like ARH suggested, I used the PVC method.....take the hose to the parts store and find one that will fit in the vent hose good.

Originally Posted by Appel_1978

so i plug the inlet on the head with a facricated plate do i need to make a gasket for it? and what about the tub going into bottom of air box and into motor? Do i plug that off as well of put a small breather filter on it

[Cravin01]

Plug or plate all three places ..move on.

P.A.I.R system delete in first mod vid

[ChipToothy]

Technically these bikes are dual exhaust..

[ChrisWNY]

What octane gas are you running in the bike? Lower octane fuels detonate quicker so you may see improvement if you fill up with a 93 super premium fuel. It may not make a difference however.

[Appel_1978]

It even does one soft puff after i turn bike off. I did the pvc inline on the crank case i even put a tiny cone filter on other end of pvc valve just for added security. I didnt do the plate yet but i did pinch hose with vise grips and had it run for 15 min to warm up and then tried revving engine and it still does it along with the puff after i turn it off. i didnt close off the hose going into carb though i didnt see the video showing that one until after my experiment. I do run the lowest grade fuel but really i have never had a bike that required that and i have changed the exhaust on all my bikes, 4 Ninjas, 1 CBR and a Suzuki Intruder 750, Never really messed with changing out any of my dirt bikes exhausts though but i was young then.